This invention relates to apparatus for use in the art of earth boring and more particularly to rotary drill heads used in drilling oil and gas wells and the like. A rotary drill head diverts flow from the borehole annulus outwardly from the wellbore and provides control over the drilling operation.
As recited in U.S. Pat. No. 4,500,094, to which reference is made for further background of this invention, rotating blowout preventors are known to those skilled in the drilling art, and are usually referred to as RBOPs; or, rotary stripper devices. The drilling of most boreholes of any significance requires at least one high pressure rotary stripper device. The RBOP enables a driving member, such as a drill string, or the kelly of a drill string, to be slidably forced axially therethrough. The RBOP includes a stripper rubber assembly rotatably mounted respective to a main body so that the driving member and stripper rubber assembly rotate in low friction relationship respective to the remainder of the RBOP. At the same time, the drill string can be slidably positioned axially respective to the RBOP as the string is moved axially within the borehole.
The present invention provides an improved, low cost, rotary drill head for diverting flow from a borehole annulus to a mud pit. The drill head has a rubber stripper assembly mounted to a stinger flange which can be removed up through the turntable and set on the derrick floor so that the stripper rubber as well as other parts of the rotary drill head can be field repaired. This enables the rotating parts of the diverter to be economically replaced, and provides a unique diverter heretofore unknown to those skilled in the art.